In the recovery of ethanol in a distillation process, recovered from grains such as corn, wheat and/or triticale, a large amount of stillage is left behind.
This stillage can be used as a feed for livestock farming, among other things.
In the conventional process up until now, the stillage is separated into thin stillage and thick stillage in a decanter. The thin stillage is fed to an evaporator for further reduction in water content and for further concentration. This process step leads to what is known as “stillage syrup”. Then, the thick stillage is mixed back in with the stillage syrup and fed to a dryer which takes the dry matter content to above 90 wt.-%. However, this recovered feed can only be fed to ruminants since the fraction of fibrous material is very high, the use of this nutritious feed additive therefore being limited to only a few areas of application.
DE 20 2009 013 389.3 discloses a device for recovering a product in which the thin stillage is concentrated by way of ultrafiltration and then is sent to a dryer together with the thick stillage. This device has essentially proven its effectiveness, but in this case as well, the product produced can only be fed to ruminants. In addition, it has been shown that in the processing of the thin stillage, ultrafiltration can only be operated economically up to a certain concentration level.